This invention relates to apparatus for measuring ligamentous insufficiency in the knee to enable a physican to provide a diagnosis of injury and evaluation of different treatment methods. In the past, abnormal motion between the tibia and the femur was detected by a physican by manipulation of the leg by hand. Often the motion of a leg with a ligament tear is subtle and difficult to compare with the patient's uninjured leg. Because even a normal knee may have a substantial motion, it is desirable to quantitatively measure the displacement to allow an accurate comparison between the patient's normal and injured knees to determine the extent of injury.
While an electromechanical instrument has been devised for measuring the anterior drawer in the legs of normal volunteers and patients with known anterior cruciate deficits in a clinical research study, the device has certain disadvantages. The instrument is expensive and bulky and is not autoclavable to allow for its use in the operating room. Also the instrument is primarily restricted to the 20.degree. anterior drawer (Lachman) test.
The apparatus of this invention is autoclavable and is designed for use in both the 20.degree. anterior draw and 90.degree. anterior draw tests and without refitting is designed for use in measuring posterior excursions. It is believed that measurement of both anterior and posterior excursions provides the physician with the maximum useful data for proper diagnosis and treatment.